<?php

namespace Aws\S3;

use Aws\Arn\Exception\InvalidArnException;
use Aws\Arn\S3\AccessPointArn;
use Aws\Arn\ArnParser;
use GuzzleHttp\Psr7;
use Psr\Http\Message\UriInterface;

/**
 * Extracts a region, bucket, key, and and if a URI is in path-style
 */
class S3UriParser {
	private $pattern = '/^(.+\\.)?s3[.-]([A-Za-z0-9-]+)\\./';
	private $streamWrapperScheme = 's3';

	private static $defaultResult = [
		'path_style' => true,
		'bucket' => null,
		'key' => null,
		'region' => null
	];

	/**
	 * Parses a URL or S3 StreamWrapper Uri (s3://) into an associative array
	 * of Amazon S3 data including:
	 *
	 * - bucket: The Amazon S3 bucket (null if none)
	 * - key: The Amazon S3 key (null if none)
	 * - path_style: Set to true if using path style, or false if not
	 * - region: Set to a string if a non-class endpoint is used or null.
	 *
	 * @param string|UriInterface $uri
	 *
	 * @return array
	 * @throws \InvalidArgumentException|InvalidArnException
	 */
	public function parse($uri) {
		// Attempt to parse host component of uri as an ARN
		$components = $this->parseS3UrlComponents($uri);
		if(!empty($components)) {
			if(ArnParser::isArn($components['host'])) {
				$arn = new AccessPointArn($components['host']);
				return [
					'bucket' => $components['host'],
					'key' => $components['path'],
					'path_style' => false,
					'region' => $arn->getRegion()
				];
			}
		}

		$url = Psr7\Utils::uriFor($uri);

		if($url->getScheme() == $this->streamWrapperScheme) {
			return $this->parseStreamWrapper($url);
		}

		if(!$url->getHost()) {
			throw new \InvalidArgumentException('No hostname found in URI: '
				.$uri);
		}

		if(!preg_match($this->pattern, $url->getHost(), $matches)) {
			return $this->parseCustomEndpoint($url);
		}

		// Parse the URI based on the matched format (path / virtual)
		$result = empty($matches[1])
			? $this->parsePathStyle($url)
			: $this->parseVirtualHosted($url, $matches);

		// Add the region if one was found and not the classic endpoint
		$result['region'] = $matches[2] == 'amazonaws' ? null : $matches[2];

		return $result;
	}

	private function parseS3UrlComponents($uri) {
		preg_match("/^([a-zA-Z0-9]*):\/\/([a-zA-Z0-9:-]*)\/(.*)/", $uri, $components);
		if(empty($components)) {
			return [];
		}
		return [
			'scheme' => $components[1],
			'host' => $components[2],
			'path' => $components[3],
		];
	}

	private function parseStreamWrapper(UriInterface $url) {
		$result = self::$defaultResult;
		$result['path_style'] = false;

		$result['bucket'] = $url->getHost();
		if($url->getPath()) {
			$key = ltrim($url->getPath(), '/ ');
			if(!empty($key)) {
				$result['key'] = $key;
			}
		}

		return $result;
	}

	private function parseCustomEndpoint(UriInterface $url) {
		$result = self::$defaultResult;
		$path = ltrim($url->getPath(), '/ ');
		$segments = explode('/', $path, 2);

		if(isset($segments[0])) {
			$result['bucket'] = $segments[0];
			if(isset($segments[1])) {
				$result['key'] = $segments[1];
			}
		}

		return $result;
	}

	private function parsePathStyle(UriInterface $url) {
		$result = self::$defaultResult;

		if($url->getPath() != '/') {
			$path = ltrim($url->getPath(), '/');
			if($path) {
				$pathPos = strpos($path, '/');
				if($pathPos === false) {
					// https://s3.amazonaws.com/bucket
					$result['bucket'] = $path;
				} elseif($pathPos == strlen($path) - 1) {
					// https://s3.amazonaws.com/bucket/
					$result['bucket'] = substr($path, 0, -1);
				} else {
					// https://s3.amazonaws.com/bucket/key
					$result['bucket'] = substr($path, 0, $pathPos);
					$result['key'] = substr($path, $pathPos + 1) ?: null;
				}
			}
		}

		return $result;
	}

	private function parseVirtualHosted(UriInterface $url, array $matches) {
		$result = self::$defaultResult;
		$result['path_style'] = false;
		// Remove trailing "." from the prefix to get the bucket
		$result['bucket'] = substr($matches[1], 0, -1);
		$path = $url->getPath();
		// Check if a key was present, and if so, removing the leading "/"
		$result['key'] = !$path || $path == '/' ? null : substr($path, 1);

		return $result;
	}
}
